The human ankle joint is a complex structure of bone, muscle, and connective tissue which is subject to tremendous physical stress in everyday and sporting activities. As a result of its inherent architecture, the ankle joint, or "mortise", is extremely stable to eversion forces which produce a rolling inward onto the medial, or inside portion of the ankle and foot. This stability, however, is sacrificed on the lateral, or outside portion of the joint, which has less bony reinforcement and weaker ligaments. Ankle inversion injuries, or sprains, typically describe a rolling outward onto the lateral aspect of the ankle and foot. This common injury frequently damages the anterior talofibular ligament, which has the unenviable task of reinforcing the anterolateral aspect of the mortise. As a consequence, permanent instability of the ankle may result.
Several types of ankle braces exist to support the ankle post-injury, but little has been done prophylactically to prevent these injuries. Most devices currently available can be bulky, uncomfortable, and expensive. Furthermore, they are not based on any biomechanical principles, which limits their ankle support function.